Varnishing a violin gives it a glossy appearance. Varnish is a transparent yet hard protective film that is used mostly on wood finishing. It is a combination of a resin, drying oil, and thinner that will make the violin appear shiny and feel smooth. A varnish is added to a violin when first made, as well as months and years later to make it continue to look new.
Ground coat the violin. This is a coating that will add colour to the wood and will have partial sealing elements included that will prevent the varnish from soaking into the wood of the violin. It is made up of a wax, glue and minerals. This is sold pre-mixed in stores that sell violins. You can also make up your own with a mixture of egg white, honey, and gum Arabic.
Develop your own varnish. Use a walnut oil combined with an amber resin. You can explore the various kinds of varnishes you feel will look best for your violin. For instance, use 45g seedlac, 7.5 grams gum elemi, 200ml alcohol, and 9ml lavender oil spike. This will need to be put into a glass jar and allowed to sit for several hours. Stir twice a day until seedlac sticks to the bottom of the jar. This will take one to three weeks. Boil for 7 minutes, let cool, and boil again for 7 minutes. Then filter until there is no dirt in the filter. Wait for it to cool in order to use as varnish.
Brush on the varnish with a small paint brush with soft bristles. This will need to be done in smooth vertical strokes in order to prevent many brush marks that will need to be touched up. Set in sun to dry.
Touch up varnish. Use a small brush and add on varnish in spots that were missed. Wait until it dries again and then remove the brush marks with an abrasive pad with 1800 to 6000 grits. This will make the violin smooth for polishing.
Polish violin with a soft cloth, mineral oil and alcohol. Use a combination of 50/50 of mineral oil and alcohol and dip the cloth into it. The mineral oil acts as a lubricant to prevent the cloth from sticking, while the alcohol eliminates the brush marks. You must keep the cloth moving in order to prevent an uneven polish.
Polish in a circlular motion and lightly in order to not remove the varnishing.